The ultimate goal of this research is to understand in molecular detail the interactions involved between the enzyme galactosyl transferase and the "modifier" protein, alpha-lactalbumin. Since general glycosyl transfer by this enzyme occurs in both male and female species in other organs, it is an important example of biological regulation when (&-lactalbumin is secreted only in lactating mammary gland to alter the specificity of the system specifically for lactose synthesis. The long term goals of this research are to (1) characterize, assign and map specific cation binding and other regions on the a-lactalbumin molecule in solution, (2) to characterize, describe and map the substrate (UDPgal) donor site, metal site(s) and (carbohydrate) acceptor site on galactosyl transferase; and (3) to describe the residues and interactions involved in the a-lactalbumin-galactosyl transferase ("lactose synthase") complex, i.e., the role of a-lactalbumin in lactose biosynthesis. These studies will involve the techniques of ESR, NMR, photo-CIDNP, fluorescence as well as biochemical and enzymological methods.